/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.linkis.rpc.interceptor.common

import org.apache.linkis.common.ServiceInstance
import org.apache.linkis.common.utils.Logging
import org.apache.linkis.protocol.{Protocol, SingleInstanceProtocol}
import org.apache.linkis.rpc.interceptor.RPCLoadBalancer

import org.apache.commons.lang3.StringUtils

import org.springframework.stereotype.Component

import com.netflix.loadbalancer.ILoadBalancer

@Component
class SingleInstanceRPCLoadBalancer extends RPCLoadBalancer with Logging {
  override val order: Int = 20

  override def choose(
      protocol: Protocol,
      originService: ServiceInstance,
      lb: ILoadBalancer
  ): Option[ServiceInstance] = protocol match {
    case _: SingleInstanceProtocol =>
      if (StringUtils.isEmpty(originService.getInstance)) synchronized {
        if (StringUtils.isEmpty(originService.getInstance)) {
          val servers = lb.getAllServers
          val server = servers.get((math.random * servers.size()).toInt)
          originService.setInstance(server.getHostPort)
          logger.warn(
            originService.getApplicationName + " choose " + server.getHostPort + " to build a single instance connection."
          )
        }
      }
      Some(originService)
    case _ => None
  }

}
